U.S. patent application number 14/517696 was filed with the patent office on 2015-04-23 for anti-diffraction and phase correction structure for planar magnetic transducers.
The applicant listed for this patent is Audeze LLC. Invention is credited to Dragoslav Colich.
Application Number | 20150110326 14/517696 |
Document ID | / |
Family ID | 52826206 |
Filed Date | 2015-04-23 |
United States Patent
Application |
20150110326 |
Kind Code |
A1 |
Colich; Dragoslav |
April 23, 2015 |
ANTI-DIFFRACTION AND PHASE CORRECTION STRUCTURE FOR PLANAR MAGNETIC
TRANSDUCERS
Abstract
An anti-diffraction plate for including in a planar magnetic
transducer. The anti-diffraction plate includes anti-diffraction
structures for positioning adjacent to magnets of the planar
magnetic transducer. By introducing a shape over top surface of the
magnets, the anti-diffraction structures cause the elimination of
diffraction patterns as a main audio wavefront passes by the
magnets from a diaphragm. A diffusion structure for diffusing
reflected sound waves, the diffusion structures reducing or
eliminating the power and capacity of the reflected sound waves to
create interference patterns with oncoming sound waves.
Inventors: |
Colich; Dragoslav;
(Huntington Beach, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Audeze LLC |
Costa Mesa |
CA |
US |
|
|
Family ID: |
52826206 |
Appl. No.: |
14/517696 |
Filed: |
October 17, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61892417 |
Oct 17, 2013 |
|
|
|
Current U.S.
Class: |
381/337 |
Current CPC
Class: |
H04R 2201/34 20130101;
H04R 7/20 20130101; H04R 7/04 20130101; H04R 9/048 20130101; H04R
9/047 20130101; H04R 9/06 20130101; H04R 2209/024 20130101; H04R
3/00 20130101; H04R 9/025 20130101; H04R 1/345 20130101 |
Class at
Publication: |
381/337 |
International
Class: |
H04R 1/34 20060101
H04R001/34 |
Claims
1. An anti-diffraction plate for a planar magnetic transducer, the
anti-diffraction plate comprising one or more anti-diffraction
structures for positioning over one or more magnets, each of said
one or more anti-diffraction structures having a surface shape for
minimizing diffraction patterns of sound waves passing by the one
or more magnets.
2. The anti-diffraction plate of claim 1, the surface shape
comprising any one or more of exponential, elliptical, parabolic,
hyperbolic, or conical profiles.
3. The anti-diffraction plate of claim 1, the anti-diffraction
plate constructed of plastic, metal or composite material.
4. The anti-diffraction plate of claim 1, the anti-diffraction
plate mounted in a planar magnetic transducer having one or more
magnets, each of said magnets having a surface shape for diffusing
reflections of sound waves.
5. A planar magnetic transducer comprising: an anti-diffraction
plate, the anti-diffraction plate comprising one or more
anti-diffraction structures for positioning over one or more
magnets, each of said one or more anti-diffraction structures
having a surface shape for minimizing diffraction patterns of sound
waves passing by the one or more magnets; the one or more magnets
having a diffusion structure that provides a surface for diffusing
reflected sound waves.
6. The planar magnetic transducer of claim 5, the diffusion
structure molded into each of the one or more magnets.
7. The planar magnetic transducer of claim 5, the anti-diffraction
structures and diffusion structure causing a smooth phase response
as measured from one or more sound waves emitted from the planar
magnetic transducer.
8. A planar magnetic transducer comprising: one or more magnets
having a diffusion structure that provides a surface for diffusing
reflected sound waves.
9. The planar magnetic transducer of claim 8, further comprising an
anti-diffraction plate, the anti-diffraction plate comprising one
or more anti-diffraction structures for positioning over the one or
more magnets, each of said one or more anti-diffraction structures
having a surface shape for minimizing diffraction patterns of sound
waves passing by the one or more magnets.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 61/892,417, filed Oct. 17, 2013, the
entirety of which is incorporated by reference as if fully set
forth herein.
FIELD OF THE INVENTION
[0002] The present invention generally relates to acoustic devices,
and more particularly, to an anti-diffraction and phase correction
structure for a planar magnetic transducer.
BACKGROUND OF THE INVENTION
[0003] Planar magnetic transducers use a flat, lightweight
diaphragm suspended in a magnetic field rather than a cone attached
to a voice coil. The diaphragm in a planar magnetic transducer
includes a conductive circuit pattern that, when energized, creates
forces that move the diaphragm in the magnetic field to produce
sound.
[0004] The structures encountered by a sound wave traveling from
the diaphragm are obstacles that may negatively interfere with the
sound wave. It is desirable for a sound wave as emitted from a
diaphragm to encounter as little interference as possible as it
travels from the diaphragm.
BRIEF SUMMARY OF PREFERRED EMBODIMENTS OF THE INVENTION
[0005] Preferred embodiments of the invention include a planar
magnetic transducer that minimizes diffraction of the main sound
wave, minimizes the effects of reflected sound waves and minimizes
the phase distortion.
[0006] A preferred embodiment of the invention includes a planar
magnetic transducer having one or more anti-diffraction structures
positioned adjacent to one or more magnets for eliminating
diffraction of a sound wave around the magnets, the sound wave
emitted from a diaphragm and passing by the magnets.
[0007] A preferred embodiment of the invention includes a planar
magnetic transducer having one or more diffusion structures
positioned adjacent to one or more magnets for minimizing
reflections of the sound wave.
[0008] A preferred embodiment of the invention includes a planar
magnetic device having one or more wave guides positioned adjacent
to one or more magnets for creating a uniform wavefront.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Preferred embodiments of the present invention are
illustrated by way of example, and not by way of limitation, in the
figures of the accompanying drawings and in which like reference
numerals refer to similar elements and in which:
[0010] FIG. 1 is a cross-section perspective view of portions of an
anti-diffraction planar magnetic transducer constructed in
accordance with some embodiments.
[0011] FIG. 2 is a cross-section elevation view of portions of the
anti-diffraction planar magnetic transducer as shown in FIG. 1.
[0012] FIG. 3 is an exploded perspective view of portions the
anti-diffraction planar magnetic transducer constructed in
accordance with some embodiments.
[0013] FIG. 4 is a diagram showing a comparison between the
movement and diffraction of sound waves without any
anti-diffraction plate, and with the anti-diffraction plate
constructed in accordance with some embodiments.
[0014] FIG. 5 is a diagram showing the movement and diffusion of
sound waves with a diffusion structure, in accordance with some
embodiments.
[0015] FIG. 6 is a diagram showing a more uniform wavefront emitted
from a planar magnetic transducer with anti-diffraction plate and
diffusion structures, in accordance with some embodiments.
[0016] FIG. 7 is a diagram showing an uneven phase response in
sound waves emitted from a planar magnetic transducer without any
anti-diffraction plate or diffusion structure, in comparison with
an even phase response in sound waves emitted from a planar
magnetic transducer with the anti-diffraction plate constructed in
accordance with some embodiments.
[0017] FIG. 8 is a graph illustrating a frequency and phase
response in sound waves emitted from a planar magnetic transducer
without any anti-diffraction plate or diffusion structure, in
comparison with a frequency and phase response in sound waves
emitted from a planar magnetic transducer with the anti-diffraction
plate constructed and diffusion structure in accordance with some
embodiments.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0018] Planar magnetic transducers comprise a flat, lightweight
diaphragm suspended in a magnetic field. A structure of magnets
coupled to stator plates are arranged at a distance from the
diaphragm to effect the magnetic field. The diaphragm in a planar
magnetic transducer includes a conductive circuit pattern that,
when energized, creates forces that move the diaphragm in the
magnetic field to produce sound.
[0019] A sound wave emitted from a diaphragm and traveling through
air in a planar transducer will encounter the magnetic structure
and stator plate as obstructions in its path of travel. The
obstructions may cause the user to hear distortions in the sound,
depending on the particular wavelength of the sound wave. If the
wavelength of the sound wave is longer then the width of the
obstruction, then the wave generally passes through without
distortion.
[0020] If the wavelength is of comparable size to the obstruction,
diffraction patterns are formed, causing distortions to the sound
wave. When the diffracted waves and the main sound wave arrive at
the listener's ears at the same time, distortion of the sound
occurs and the stereo imaging is affected. When sound waves go
around the obstacle they arrive at the listener's ear at slightly
different times compared to the main sound wave, causing phase
distortion.
[0021] If the wavelength is smaller than the obstruction, then in
addition to diffraction patterns, the sound wave is reflected. The
reflected sound waves interact with new sound waves emitting from
the diaphragm to create constructive and destructive interference
patterns at certain frequencies, causing further distortion.
Further, the space between the obstructions can create resonant
chambers which influence frequency response.
[0022] Preferred embodiments of the invention include a planar
magnetic transducer that minimizes diffraction of the main sound
wave, minimizes the effects of reflected sound waves and minimizes
the phase distortion. A preferred embodiment of the invention
includes an anti diffraction structure that can be considered as a
particular version of a wave guide planar magnetic transducer
having one of more wave guides positioned adjacent to one or more
magnets.
[0023] FIGS. 1-3 show various views of portions of a planar
magnetic transducer according to some embodiments. FIG. 1
illustrates a perspective and cut-away, section view, and FIG. 2
illustrates the cut-away portion in a front elevation view. As
assembled in the planar magnetic device, FIG. 1 shows an array of
magnets 10 positioned adjacent to one side of an anti-diffraction
plate 12, the anti-diffraction plate having one or more
anti-diffraction structures 16. In some embodiments, the
anti-diffraction structures 16 are aligned with array of magnets 10
such that each bottom side edge of an anti-diffraction structure is
flush with each top side edge of a magnet. For example, edge 18 of
an anti-diffraction structure is flush with edge 20 of a magnet of
array 10. In the device, a diaphragm 14 is mounted such that
diaphragm 14 is spaced at a distance from array of magnets 10 to be
within the magnetic field of array 10 when the planar magnetic
device is assembled. For example, rivets may be introduced into
holes 22 to mount diaphragm 14 at an appropriate distance. Other
mounting techniques may be used to achieve the suspension of
diaphragm 14 without departing from the spirit of the invention.
Anti-diffraction plate 12 further comprises one or more gaps or
apertures between anti-diffraction structures 16 for allowing sound
waves traveling from diaphragm 14 to pass by plate 12.
[0024] One of the primary objectives of preferred embodiments is to
create a uniform wavefront that results in much smoother frequency
response, better imaging, smoother phase response, better high
frequency extension and higher efficiency. Anti-diffraction plate
12 eliminates the resonant chambers in front of the diaphragms and
creates an acoustic chamber with higher pressure. Higher pressure
creates a better acoustical impedance match between diaphragm and
air increasing the efficiency of the transducer and creates better
high frequency extension. Anti-diffraction plate 12 can be used
with standard long bar magnets to achieve the reduction in
diffraction in a cost-effective way.
[0025] FIG. 2 illustrates a front elevation cut-away view of the
structures show in FIG. 1, according to some embodiments. As shown,
array of magnets 10 are disposed over diaphragm 14. An
anti-diffraction structure of the plurality of anti-diffraction
structures 16 of anti-diffraction plate 12 is positioned adjacent
to each of the magnets in array 10. Gaps or apertures 24 and mounts
22 are also shown.
[0026] Referring to FIGS. 1 and 2, the shape of the top surface an
anti-diffraction structure of the plurality of anti-diffraction
structures 16 is a shape that minimizes or eliminates diffraction
of a sound wave traveling from diaphragm 14 as the sound wave
passes by the magnets and plate. While FIGS. 1 and 2 show a
particular shape for the anti-diffraction structures, it is
understood by those of ordinary skill in the art that any shape
capable of eliminating or maximizing the reduction of diffraction
of the sound wave emanating from diaphragm 14 is contemplated as
being within the scope of embodiments of the invention.
Cross-sectional shapes of the anti-diffraction structure includes
but are not limited to exponential, elliptical, parabolic,
hyperbolic, or conical profiles.
[0027] Further, while anti-diffraction plate 12 is shown in a
particular configuration and as a circular shape, and while array
10 is shown with three magnets of a particular shape, size or
configuration, it is understood that variations on the structures,
including different quantity, shape, and dimensions of array 10 and
anti-diffraction plate 12, are within the scope of the embodiments
of the invention.
[0028] FIG. 3 illustrates an exploded view of array of magnets 10,
anti-diffraction plate 12, and diaphragm 14 according to some
embodiments. Array 10, plate 12, and diaphragm 14 are components of
a planar magnetic transducer (not shown).
[0029] Anti-diffraction plate 12 may be constructed from any
suitably rigid material that will not interfere with the magnetic
forces of the magnets, including plastic, metal, or composite
materials. In a preferred embodiment, anti-diffraction plate 12 is
made of a rigid plastic material mounted adjacent to magnet array
10. Long bar magnets are spaced in parallel, in alignment with the
anti-diffraction structures 16 of plate 12. The shape of each
anti-diffraction structure comprises a flat bottom surface, and a
curved top surface.
[0030] FIG. 4 illustrates two examples of portions of planar
magnetic devices in operation, where view 400 shows the effect of
the absence of any anti-diffraction structures on the magnets, and
view 402 shows the effect of the anti-diffraction structures on the
magnets. View 400 shows a main audio wavefront 26 traveling from
diaphragm 14 of the planar magnetic device. As the wavefront 26
passes by the edges of the top of the magnets, the "corner" shape
30 of the magnets as seen in cross-section causes diffraction
patterns 28 to be generated, and introduces distortion into the
sound.
[0031] In contrast, view 402 shows a main audio wavefront 32
traveling from diaphragm 14 of the planar magnetic device. As
wavefront 32 passes the combined structures of the anti-diffraction
structures 16 positioned adjacent to the magnets, diffraction
patterns are eliminated or minimized due to the surface shape of
the anti-diffraction structures 16. The anti-diffraction structures
16 accordingly smooth out the "corner" shape of the of the magnets
as seen in cross section, eliminating or reducing diffraction
waves. The anti-diffraction structures 16 cause a smoother
frequency response and a more precise imaging of the sound
wave.
[0032] In addition to distortion of the sound waves from the
diaphragm caused by diffraction as described above, sound waves of
a particular wavelength may be reflected off the surface of the
magnet facing the diaphragm, interfering with oncoming sound waves
generating from the moving diaphragm. FIG. 5 is a diagram showing
diffusion structures 34 that diffuse the power of the reflections
to minimize the interference caused by reflection. As sound waves
32 travel from the diaphragm 14, they encounter the bottom surface
of the magnet array 10 as shown. Diffusion structures which
provides a curvature or other diffusing surface to the bottom
magnet surface diffuses the reflected sound pressure waves in
different directions, shown as diffused waves 36, greatly reducing
or eliminating their power and capacity to create interference
patterns with oncoming sound waves. In some embodiments, the long
bar magnets are manufactured or shaped with diffusion structures
36. In some embodiments, the diffusion structures are mounted
adjacent to the bottom surface of the magnets as shown.
[0033] FIG. 6 is a diagram illustrating a planar magnetic
transducer having both an anti-diffraction plate with diffusion
structures for creating a uniform wavefront. Sound waves generated
from moving diaphragm 14 travel and encounter diffusion structures
34, apertures 24, and anti-diffraction wave guide structures. Due
to the diffusion of reflected waves caused by diffusion structures
34, and the elimination of diffraction patterns from the presence
of the anti-diffraction structures, a generally uniform wavefront
42 emerges from the apertures of the magnet array 10.
[0034] FIG. 7 are a set of diagrams illustrating a comparison
between the phase response of sound waves passing through a planar
magnetic transducer 700 with a standard long bar magnet array, and
the phase response of sound waves passing through a planar magnetic
transducer 702 with a modified long bar magnet array with the
structures as described in FIGS. 1 to 6 above. When diffraction
patterns 28 and reflected sound waves 44 occur, sound waves 46 are
not smooth and do not provide a smooth phase response 50. In
contrast, when diffraction patterns are reduced or eliminated, and
the reflected sound waves are diffused, as shown with planar
magnetic transducer 702, sound waves 48 are smooth and provide a
smooth phase response 52.
[0035] FIG. 8 is a graph illustrating a frequency and phase
response in sound waves emitted from a planar magnetic transducer
without any anti-diffraction plate or diffusion structure, in
comparison with a frequency and phase response in sound waves
emitted from a planar magnetic transducer with the anti-diffraction
plate constructed and diffusion structure in accordance with some
embodiments. FIG. 8 shows a graph having frequency response line 54
and phase response line 56 produced by a planar transducer without
any anti-diffraction or diffusion structures, in contrast with
frequency response line 58 and phase response line 60, produced by
planar magnetic transducer according to some embodiments of the
invention having anti-diffraction and diffusions structures. With
use of anti-diffraction and diffusions structures in the planar
magnetic transducers in accordance with some embodiments, frequency
response is smoother, has higher efficiency and better extension
than without the novel structures, and a near-linear phase
response.
[0036] Other features, aspects and objects of the invention can be
obtained from a review of the figures and the claims. It is to be
understood that other embodiments of the invention can be developed
and fall within the spirit and scope of the invention and
claims.
[0037] The foregoing description of preferred embodiments of the
present invention has been provided for the purposes of
illustration and description. It is not intended to be exhaustive
or to limit the invention to the precise forms disclosed. Various
additions, deletions and modifications are contemplated as being
within its scope. The scope of the invention is, therefore,
indicated by the appended claims rather than the foregoing
description. Further, all changes which may fall within the meaning
and range of equivalency of the claims and elements and features
thereof are to be embraced within their scope.
* * * * *